Only a matter of time

[mattdavala]

Hey everyone!

I've been activly reading the videoKarma TV groups every day but I haven't posted here do to a lack of projects. The economy's been hindering any puchase of a vintage TV and my current collection has been working pretty well. My 1955 21 inch majestic console had been running with the origional electrolytics for well over a year. I'd replaced all paper caps when I aquired the TV.

The electros ran cool to the touch so I hadn't replaced them. I knew the risk of not replacing them, but set ran well with them. I was happily watching the three stooges when the TV's volume blasted with a 120 cycle hum! The voices were normal but there was a full volume 120 cycle hum thats not controllable by the volume control. Sooooo loud! I had to do the infamous mad dash across the room to shut the set off.

I'm glad the cap opened vs shorting out. So I'll be repaceing all electrolytic caps in the set now. I'm actually glad to have a project to work on. Got my order sent in to Justradios already.

Best regards,
matt Davala

[Phil Nelson]

I am going to save your little story for the next time someone crows about how their radios & TVs run perfectly with original electrolytics. May be true . . . for a while.

If my cap order arrives today, I'll be doing the same chore on my CTC-11. The old electros have held up during initial tryouts, but I'd like to be able to watch it without one hand hovering over the power switch

Phil Nelson

[wa2ise]

Originally Posted by Phil Nelson

I am going to save your little story for the next time someone crows about how their radios & TVs run perfectly with original electrolytics. May be true . . . for a while.



Phil Nelson

I've had to replace can electrolytics lately, one in a late 40's Zenith radio, another set in a 1950 Admiral B&W TV, and in a stereo amplifier, a Dynaco SCA35. Must be time for the chickens to roost. Looks like they lasted about 20 years longer than cardboard tube electrolytics.

I've done the "pair of caps in series" to replace 450V caps. A pair of 250V caps, same capacitance, with 1 watt 1 megohm resistors across each cap, to be sure the voltage divides evenly across the pair. Mounted them on terminal strips under chassis, leaving the old caps unconnected but still present.

[jeyurkon]

Mattdavala's story is appropriate for your situation in that he didn't test the electrolytics, or rather only tested them by feeling them. It still doesn't change my opinion of the procedure I used.

But having said that, I still feel that you'd be better off changing all of yours.

My 1-108 chassis Sylvania shares many of the same vintage parts that your 1-387 does. While I didn't change all of the electrolytics, I found many that were bad or questionable. They either had high leakage or a high ESR or both. This was especially true for the horizontal section. I think you can expect the same even though your set is a couple of years younger.

Bringing the set up slowly with a variac may let the electrolytics reform, but without testing them you still don't know the state of their health and they may cause problems and prolong your trouble shooting.

I would at least replace all of the electrolytics that are not vertical can mounted ones. If you keep those, I would add fuses where appropriate to protect the transformer.

John